The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
A seat provided in a vehicle includes a seatback supporting the upper body of an occupant, a seat cushion supporting the lower body of the occupant including the buttocks and the thighs, and a headrest supporting the back part of the head. A reclining device allowing the angle of the seatback to be adjusted in the forward and backward direction with respect to the seat cushion is disposed on the portion in which the seatback and the seat cushion is connected to each other.
The reclining device is divided into a manual reclining device, in which the occupant adjusts the angle of the seatback by manipulating a lever, and a power-type reclining device that automatically operates using power from a motor in response to a switch being manipulated. All reclining devices must have a strong coupling force between parts during the reclining operation in order to ensure that occupants are safe regardless of the operating scheme.
FIGS. 1 and 2 illustrate a reclining device of the related prior art having a cam structure. The reclining device includes a mobile flange 1, a gear plate 2, a bearing 3, first and second cams 4 and 5, an input device 6, a spring 7, a push nut 8, and a retainer 9. The mobile flange 1 has an internal gear 1a and a cylindrical flange protrusion 1b formed on the central portion thereof. The gear plate 2 has an external gear 2a meshing with the internal gear 1a and a cylindrical plate protrusion 2b formed on the central portion thereof. The bearing 3 is fitted into the plate protrusion 2b. One portion of the bearing 3 is supported on the mobile flange 1, and the outer circumference of the bearing 3 adjoins the inner circumference of the plate protrusion 2b. The first cam 4 and the second cam 5 are disposed in the space between the outer circumference of the flange protrusion 1b and the inner circumference of the bearing 3 such that the first cam 4 and the second cam 5 overlap each other. The input device 6 has a central protrusion fitted into the flange protrusion 1b, a cover part 6b bent outward from one end of the device protrusion 6a, and a support 6c bent from the distal end of the cover part 6b in the direction of the mobile flange 1. The spring 7 is positioned in the space between the distal end of the flange protrusion 1b and the cover part 6b. Both ends of the spring 7 are fitted into the first and second cams 4 and 5. The push nut 8 is fitted into the plate protrusion 2b and adjoins the cover part 6b of the input device, thereby maintaining the assembled state of the input device 6. The retainer 9 couples the mobile flange 1 and the gear plate 2 to each other by surrounding the outer circumference of the mobile flange 1 and the gear plate 2.
The recliner shaft is coupled to the central protrusion 6a of the input device 6. The support 6c of the input device 6 adjoins both the bearing 3 and the second cam 5. The push nut 8 is interference-fitted into the plate protrusion 2b and fixedly adjoins the cover part 6b of the input device 6.
The mobile flange 1 is coupled to the back bracket 210, which is coupled to the seatback frame 220. The gear plate 2 is coupled to the cushion bracket 230, which is coupled to a seat cushion back frame (not shown).
Here, the gear plate 2 and the cushion bracket 230 are coupled to each other by means of a weld W1 in order to increase coupling force. Most the heat produced during welding is transferred to the bearing 3 through the plate protrusion 2b, which may damage a coated surface 3a of the bearing 3.
The reclining device of the related prior art is configured such that the outer circumference of the bearing 3 directly adjoins the inner circumference of the plate protrusion 2b of the gear plate 2 and the first and second cams 4 and 5 adjoin the inner circumference of the bearing 3. When the gear plate 2 and the cushion brackets 230 are coupled to each other by means of the weld W1, the heat produced during the welding is transferred to the bearing 3 through the plate protrusion 2b, whereby the coated surface 3a of the bearing 3 adjoining the first and second cams 4 and 5 may be damaged by the welding heat.
The inner circumference of the bearing 3 forms the coated surface 3a in order to facilitate the operation of the first and second cams 4 and 5. If the coated surface 3a of the bearing 3 is damaged by high-temperature welding heat the performance of the first and second cams 4 and 5 may be degraded.
In addition, in the reclining device of the related prior art, a gap C1 is present between the inner circumference of the plate protrusion 2b and the push nut 8. This allows a coating solution to enter through the gap C1, thereby causing possible contamination of the bearing 3 and the first and second cams 4 and 5. This consequently may degrade the performance of the operation of the bearing 3 and the first and second cams 4 and 5.
Furthermore, since the plate protrusion 2b of the gear plate 2 and the cushion bracket 230 are coupled to each other by means of the weld W1, the load of the seat and the occupant is transferred to the plate protrusion 2b through the cushion bracket 230. As illustrated in FIGS. 1 and 3, in the reclining device of the related art, the gear plate 2 is an open-type in which the plate protrusion 2b is open without any support structure. Consequently, the gear plate 2 including the plate protrusion 2b may be easily twisted, thus reducing the endurance of the reclining device.
In addition, as illustrated in FIGS. 1 and 4, the reclining device of the related prior art is configured such that the retainer 9 couples the mobile flange 1 and the gear plate 2 by surrounding both the outer circumference of the mobile flange 1 and the outer circumference of the gear plate 2. When the gear plate 2 is subjected to twisting, the portion M1 of the retainer 9 supporting the gear plate 2 warps as indicated by an arrow R1. The warped portion M1 causes the retainer 9 to become loose. This consequently decreases the coupling force of the retainer 9, thereby weakening the coupling between the mobile flange 1 and the gear plate 2.
Furthermore, since the retainer 9 of the related prior art requires a portion M2 surrounding both the outer circumference of the mobile flange 1 and the outer circumference of the gear plate 2, an additional amount of time is required to shape and form the retainer, thus increasing fabrication costs and also increasing the weight of the retainer.
The information disclosed in the Background of the present disclosure section is only for the enhancement of understanding of the background of the present disclosure, and should not be taken as an acknowledgment or as any form of suggestion that this information forms a prior art that would already be known to a person skilled in the art.